Preheat oven to 400°F (200°C). Season chicken with salt and pepper, place in a baking dish, and drizzle with olive oil.

In a saucepan, heat balsamic vinegar over medium heat until simmering. Reduce for 10-15 minutes until thickened.

Chop bell peppers, zucchini, and red onion into bite-sized pieces. Toss in a bowl with olive oil, salt, and pepper.

Bake chicken for 15 minutes. Drizzle half of the balsamic glaze over the chicken and add veggies. Bake for an additional 20-25 minutes.

Drizzle remaining balsamic glaze over and bake for another 5 minutes. Chicken should be golden brown.

Let rest for a few minutes before serving on a platter.